Here's another set of frequently asked questions (FAQs) about doing design of experiments (DOE), plus alerts to timely information and free software updates. If you missed the previous DOE FAQ Alert, please click on the links at the bottom of this page. If you have a question that needs answering, click the Search tab and enter the key words. This finds not only answers from previous Alerts, but also other documents posted to the Stat-Ease web site.
Feel free to forward this newsletter to your colleagues. They can subscribe by going to http://www.statease.com/doealertreg.html. If this newsletter prompts you to ask your own questions about DOE, please address them via mail to:StatHelp@StatEase.com.
For an assortment of appetizers to get this Alert off to a good start, see these new blogs at http://statsmadeeasy.net:
1. Newsletter alert: March issue of the Stat-Teaser features new release of Design-Expert® software
1. Newsletter Alert: March issue of the Stat-Teaser features new release of Design-Expert software
Many of you will soon receive a printed copy of the latest Stat-Teaser, but others, by choice or because you reside outside of North America, will get your only view of the March issue at http://www.statease.com/news/news0703.pdf.
This issue of the Stat-Teaser features version 7.1 of Design-Expert (DX7.1). DX7.1 beefs up power and design capabilities and offers clever new interface features that make design and analysis easier than ever. For a free, fully-functional trial, click http://www.statease.com/dx7trial.html and/or view tutorials at http://www.statease.com/dx71_man.html. See pricing for new licenses or upgrades at our e-commerce site: http://www.statease.com/prodsoft.html.
Also featured in this issues of Stat-Teaser is the new DOE for DFSS: Variation by Design Workshop, which will achieve its inaugural presentation on June 20-21 at our Minneapolis training center. For more details on this class, see http://www.statease.com/clas_ddfss.html. From there you can enroll on-line via internet e-commerce.
2. FAQ: Can responses with missing data still be analyzed?
"I am doing a normal 2^3 experiment with 2 replicates. I will not be able to use one of the response values. Can I make analysis in a normal way. I believe that your software gives you some kind of a warning!?"
*In 1990, George Box wrote on "A Simple Way to Deal with Missing Observations from Designed Experiments" in Quality Engineering magazine (Vol. 3, #2, pp 249-254). Recognizing that not everyone had access to computers that provided regression tools — Box's first choice, he advised a simpler procedure to plug in a "fitted value" for the missing observation developed originally by Yates in 1933! We've come a long way over the four-score years since this pioneering work in the field of DOE.
3. Info Alert: "Space Shuttle Debris Impact Tool Assessment Using the Modern Design of Experiments"
Dick DeLoach of NASA Langley Research Center is lead author of an article detailing application of DOE tools to quantify the impact of cavity geometry error on estimates of thermal and structural reentry loads on the Space Shuttle. See this at http://www.statease.com/pubs/spaceshuttledebris.pdf. The paper stemmed from a presentation to the 45th AIAA Aerospace Sciences Meeting earlier this year. The article credits Stat-Ease Consultants Wayne Adams and Pat Whitcomb for their "invaluable assistance in accounting for nonlinear factor constraints in the design of these experiments." :)
4. Book Alert: Ryan's "Modern Experimental Design" and a new text by Box and Draper on response surface methods (RSM)
John Wiley & Sons just published two books on DOE and RSM
— "Modern Experimental Design" by Thomas P. Ryan: See details at http://www.wiley.com/WileyCDA/WileyTitle/productCd-0471210773.html. Page 1 of the book states that "Software is almost indispensable in designing experiments...special purpose software...will be needed in some circumstances...with strong emphasis on Design-Expert, which has certain features reminiscent of expert systems..." :)
— "Response Surfaces, Mixtures and Ridge Analysis" by George E. P. Box, Norman R. Draper offers much more than their previous textbook "Empirical Model-Building and Response Surfaces" (1987), but at 857 pages it is very hefty! See more information at http://www.wiley.com/WileyCDA/WileyTitle/productCd-0470053577.html. Note they included as problem 5-35 my DOE on a bread making machine that Quality Progress magazine published in their May 2003 issue.* I am proud to achieve mention in this book by Box and Draper. :)
*Manuscript at http://www.statease.com/pubs/ruggednesstest.pdf.
5. Event Alert: Stat-Ease out and about
Click http://www.statease.com/events.html for a list of appearances by Stat-Ease professionals. We hope to see you sometime in the near future!
PS. Do you need a speaker on DOE for a learning session within your company or technical society at regional, national, or even international levels? If so, contact me. It may not cost you anything if Stat-Ease has a consultant close by, or if a web conference will be suitable. However, for presentations involving
6. Workshop Alert: See when and where to learn about DOE
See http://www.statease.com/clas_pub.html for schedule and site information on all Stat-Ease workshops open to the public. To enroll, click the "register online" link on our web site or call Stat-Ease at 1.612.378.9449. If spots remain available, bring along several colleagues and take advantage of quantity discounts in tuition. Or consider bringing in an expert from Stat-Ease to teach a private class at your site.*
*Once you achieve a critical mass of about 6 students, it becomes very economical to sponsor a private workshop, which is most convenient and effective for your staff. For a quote, e-mail email@example.com.
I hope you learned something from this issue. Address your general questions and comments to me at: Mark@StatEase.com.
Mark J. Anderson, PE, CQE
PS. Quote for the month — Profound insights on RSM model-building:
Acknowledgements to contributors:
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